Which improvement did the shipping container bring?

answer: a

explanation:  

stocks and bonds are the two main classes of assets investors use in their portfolios. stocks offer an ownership stake in a company, while bonds are akin to loans made to a company (a corporate bond) or other organization (like the u.s. treasury). in general, stocks are considered riskier and more volatile than bonds.

savings accounts are just money in a bank- they are insured by the fdic for up to 250,000.   very little risk

the average mutual fund holds hundreds of different securities, which means mutual fund shareholders gain important diversification at a low price. which means if one stock or bond drops it will have very little affect on the mutual fund - again very little risk